We want to point out that recently, in the context of flat holography, the (modified-)Mellin transformations of the \(1+3\) D space-time scattering amplitudes of mass-less particles have been shown in [1]} to be equal to the \(1+2\) D CCFT correlators that have spatial Dirac-delta function factors. This kind of CCFT correlators was earlier observed in [2]}, [3]}. But, in the BMS\(_3\)  free scalar model [4]}, if the following basic correlator [3]}:
\(\left\langle \phi (t_1,x_1)\phi (t_2,x_2)\right\rangle =t_{12}\delta (x_{12})\) 
